Motor operated tuning means



y 1958 B. A. scHwARz ET AL 2,835,817

MOTOR OPERATED TUNING MEANS Original Filed Oct. 31, 1950 6 Sheets-Sheetl K 55 65 80 I00 I20 I40 I60 11mm... W

y 1958 B. A. SCHWARZ ET AL 2,835,817

MOTOR OPERATED TUNING MEANS Original Filed Oct. 31, 1950 6 Sheets-$heet2 I 3 nventors y 1958 B. A. SC-HWARZ ET AL 2,835,817

MOTOR OPERATED TUNING MEANS Original Filed Oct. 31, 1950 6 Sheets-Sheet3 ISnnentors (Ittornegs May 20, 1958 Original Filed Oct. 31, 1950 B. A.SCHWARZ ET AL 2,835,817

MOTOR OPERATED TUNING MEANS 6 Sheets Sheet 4 ZSnventors Ottornegs May20, 1958 BA. SCHWARZ ETA], 2,335,817

MOTOR OPERATED TUNING MEANS Original Filed 001:. $1, 1950 6 Sheets-Sheet5 l ISnventors (Iltornegs y 1958 B. A. SCHWARZ ET AL 2,835,817

MOTOROPERATED TUNING MEANS Original Filed Oct. 31, 1950 6 Sheets-Sheet 6Zinnentors 4? ig @z/zaw (Ki/W27} Bu Kw (Ittornegs Unite MOTQR OPERATEDTUNING MEANS Bertram A. Schwarz and Manfred G. Wright, Kokomo, Ind,assignors to General Motors Corporation, Detroit, Mich., a corporationof Delaware 1 Claim. (Cl. 250-40) This invention relates to means fortuning radio receivers over a predetermined portion of the spectrum andmore particularly to automatic indexing means for stopping said tuningmeans on desired stations upon receipt of an incoming signal, and is adivision of Serial No. 193,148, filed October 31, 1950 issued as Patent2,701,330 on February 1, 1955. Radio broadcast receivers are normallyequipped with manually movable means, the movement of which in turnmoves one part of a tuning assembly to cause the radio receiver to betuned to various frequencies in sequence over the band. The tuning meansitself may take the form of a variable condenser or a variableinductance, but for both there must be provided relatively movableparts, the relative motion of which creates a change in capacity orinductance to tune the associated resonant circuits to differentfrequencies and thus tune the receiver to different incoming stations.

After radio receivers having what might be termed straight manual tuninghad been onthe market for some time, push button tuners were introducedin which a plurality of buttons carried on the ends of movable armsmounted in the radio chassis were provided, the movement of whichselectively moved the tuning means to different positions associatedwith desired radio stations and, depending upon the mechanicaladjustment of parts, to different positions. These mechanical partscould be adjusted and then locked in position so that each time the pushbutton was moved, the set would be turned to a given station. If it weredesired to have any one of these push buttons set to a new and differentstation, the mechanical means had to be unlocked, the set tuned, themechanical means re-set and locked, and thereafter it would tune in thenew station.

However, in the operation of radio receivers which are mounted onautomotive vehicles, it was found that the daytime range is relativelylimited and, therefore, the driver, if he were attempting a trip of anydistance, would soon find that the stations set up on his push buttonswere no longer available, and would either have to reset to a new seriesof stations in his area at the moment or use the straight manual tunerstill available.

Tuning means have been devised to overcome the necessity for previouslyadjusting or setting devices for incoming stations. These tuning systemshave been called stop-on-signal tuners or signal tuning tuners and areactuated by the presence and strength of an incoming signal in thereceiver itself and of course do not require any mechanicalpreacljustment. They tune the set accurately to an incoming carrierwhich is transmitting and otherwise scan the spectrum.

It is an object of our invention to provide a tuning mechanism for highfrequency transmission receiver means actuated to index by the presenceof an incom ing transmitted wave.

It is a further object of our invention to provide a signal actuatedtuning means which scans the frequency spectrum in one direction and isquickly returned to the States Patent ice opposite limit of travel, theindexing means being operative only in the scanning direction ofmovement.

it is a further object of our invention to provide a power operatedsignal indexing tuning mechanism that may also be manually tuned.

It is a further object of our invention to provide a signal actuatedtuning means having novel speed control and indexing means for stoppingthe same.

It is a still further object of our invention to provide a signalactuated tuning means having a speed control and indexing meansincluding a differential drive also operable by manual means.

With these and other objects in view which will become more apparent asthe specification proceeds, our invention may be better understood byreference to the following specification and claims and theillustrations in the accompanying drawings in which:

Figure l is a front elevation of the control panel of a radio receiverembodying our invention.

Figure 2 is a top plan view of the tuner with parts of the casing brokenaway to reveal the interior construction.

Figure 3 is an enlarged sectional view taken on the line 3-3 of Figure2.

Figure 4 is a bottom plan View of the tuner with the casing removedtaken on the line 4-4 of Figure 3.

Figure 5 is an enlarged top plan view of the detail gear train andplanetary assembly.

Figure 6 is a side elevation of the gear train and planetary assemblytaken on the line 6-6 of Figure 5 in the direction of the arrows.

Figure 7 is a bottom plan view of the gear trainand planetary assemblytaken on the line 7-7 of Figure 6 in the direction of the arrows showingthe reverse side to that shown in Figure 5 with parts broken away.

Figure 8 is a detail elevation of the shaft and gearing carried by theplanetary carriage taken on line 8-8 of Figure 10 in the direction ofthe arrows.

Figure 9 is a sectional view of the planetary gear assembly taken onlines 9-9 of Figure 10 and Figure -5.

Figure 10 is a sectional view taken on the line 10-10 I of Figure 9.

Figure 11 is a bottom plan viewof the tuner with the casing removed andparts broken away; and

Figure 12 is a sectional view of a part of the gear train and planetaryassembly taken on the line 12-1 2 o f Figure 5.

As previously mentioned the type of tuner herein described is thatdesigned to scan a frequency spectrum, which in this case is the radiobroadcast spectrum but which obviously may be any desired span, and tostop or index at any point in the spectrum where a signal is received,solely by the appearance of said signal in the system. In order to causesaid apparatus to scan the band for which it was designed there isprovided tuning means 2 supported on a frame 4. The tuning meansconsists of a set of inductances or coils 6 which are connected into thevarious resonant circuits of the receiver. The variation in theinductance values of these coils is provided by commiuuted iron cores 8commonly mounted on a movable cross bar 10 which has slot 12 in one endriding on track section 14 of the frame 4.

A longitudinal rod 16 mounted in the frame parallel to the track sectionand approximately halfway between the two side frame members, extendsthrough an opening in the cross bar 10 and acts as an additional supportand guide. Thus movement of the bar along the track and rod eitherplunges the cores 8 into or retracts them from their associated coils 6depending on the direction of movement and thus tunes the receiver.

Some of the earlier forms of signal actuated tuners had the movabletuning means actuated by small electric motors and tuned slowly in bothdirections over the band. The present design does not provide two-wayscanning but instead provides a scanning action and indexing control inone direction only, namely from the low frequency to the high frequencyend of the band and then a quick return to the low frequency end duringwhich the indexing means is disabled. The cross bar is thereforeprovided with means to drive it relatively slowly toward the front ofthe tuner and away from the coils and then quickly return it to aposition adjacent the coils again in which the cores are inserted to themaximum distance within their associated coils.

The driving force for the tuning movement is provided generally byenergy stored in a resilient means, the motion being slowed down to asatisfactory rate by a gear train load and a governor. When theresilient means has expanded the energy stored therein a cocking meansis provided to recharge the same and this recocking action is quicklyperformed and physically moves the parts back to the beginning of thetuning motion cycle.

A plate 18 having a large opening 20 therein has an upturned flange 22at one end, a pair of spaced upturned flanges 24 near the opposite endand a central flange 26 extending beyond the two flanges 24 and betweenthem. The flanges 24 are rigidly secured to the rear face of the crossbar 10 by any suitable means to form a unitary assembly of the twoparts. The flanges 22 and 26 are aligned on the longitudinal axis of theplate 18 and are provided with openings therein through which the rod 16projects. Plate 18 therefore provides further support for the bar 10 onthe rod 16 and also connection to the driving means.

The top plate 28 of the frame 4 has rigidly connected thereto in spacedparallel relation by bolts 34 two plates, and 32, which act as amounting for the gear train assembly. A shaft 36 is rotatably supportedin aligned openings in the plates 30 and 32 and extends beyond bothplates for a short distance. A plurality of gears 38, 40 and 42 andspacers 44 and 46 are all mounted on the shaft. Gear 38 and pinion 40are secured together to rotate as a unit but are loose on the shaft.Spacer 46 and gear 42 are rigidly secured to the shaft and rotatetherewith. -A second shaft 48 parallel to the shaft 36 is also rotatablymounted in the two plates and carries a gear 58 and a pinion 52 fixedlysecured thereto. A third shaft 54 likewise rotatably mounted in theplates completes the gear train carried thereby. On this shaft arefixedly mounted a pinion 56 and an air governor 58 consisting of aplurality of fan blades affixed to a hub. The gear train from shaft 36to the air governor may be identified as follows: gear 38, pinion 52,gear 50 rotatable therewith and pinion 56 to the governor.

A planetary carriage for supporting gears in planetary relation to thoseon shaft 36 is provided by two spaced plates 60 and 62 held in desiredrelation by a plurality of bolts 63. These two plates are spaced fartherapart than plates 30 and 32 and project over and under the first plateassembly. The two plates are not of the same configuration but havedifferent projecting portions for connecting to the carriage the otheroperating parts. The plates 60 and 62 are provided with aligned openings64 and 66 through which the projecting ends of shaft 36 are adapted topass thus providing a pivot for the planetary carriage on the gear trainhousing.

The planetary carriage is also provided with a second pair of alignedopenings in which a shaft 68 is rotatably supported. The details of theassembly carried on shaft 68 are best shown in Figures 8, 9 and 10. Aflanged sleeve 70 is staked to the shaft 68 and loosely confines largegear wheel 72. A circular Wheel 74- having one side face of a dishedcontour as shown at 76 is mounted on said shaft but may be rotated withrespect thereto. The wheel 74 has an axially extending hub 73 on theopposite side from the dished face and thicker than gear 72 upon whichthe gear wheel 72 is mounted loosely 4 l and may rotate. A second andlarger hub 80 is provided on said wheel '74 offset from the first andacting as a mounting for ratchet gear 82 rigidly affixed thereto, sothat it will he immediately next to the gear Wheel 72. A spring disc 84of friction material is next mounted on the shaft 63 and held in contactwith a circular surface 86 adjacent the periphery of the wheel 74. Thedisc 84 is held in position by pinion 88 which is pressed onto the shaft68. The disc is kept from turning on the shaft 68 by a key 90 whichengages the teeth of pinion 88.

A pawl and ratchet connection is provided between the gears 72 and 88 sothat they will rotate as a unit in one direction but rotateindependently in the opposite direction. A pawl 92 is pivotally mountedon the lower surface of the gear 72 and is adapted to engage the teethof the ratchet wheel 82. An arcuate spring arm 94 rigidly aflixed to thegear face 72 at points 96 bears upon the pawl 92 to maintain it incontact with the ratchet teeth.

The movement of the planetary assembly unit about the axis of the shaft36 provides the driving motion or force for the tuning means. Referringparticularly to Figure 4, it will be seen that the lower plate 62 of theplanetary assembly is provided with an extending lug 98 to which ispivotally connected a link 100, the opposite end of which is likewisepivotally connected to the plate 18 of the crossbar assembly. Thusrotary movement of the planetary unit moves the crossbar and cores backand forth for tuning. The planetary assembly may be caused to move aboutits pivot and to drive the tuning means due to several different means.As previously mentioned in the specification, the drive for the tuningmeans in scanning the band is due to a spring member or resilientstorage means. This force is supplied through a heavy coil spring 102,best shown in Figure 5, which has one end connected to an upturned tang104 on plate 60 of the planetary assembly, and its opposite endconnected to a stationary bolt 34 rigidly secured to the frame. Thus inFigure 5 the spring 102 will bias the planetary assembly to rotate in acounterclockwise direction, as viewed in that figure, when gear 42 islocked by the manual drive, and this planetary movement will cause thecrossbar tuning assembly to move toward the front of the tuner, asviewed in Figure 11. This motion is damped or slowed to a rateacceptable for tuning by the gear train and governor 58 associatedtherewith.

When the spring has rotated the planetary assembly as far as it isdesired, an adjustable stop 106 in the form of a rotatable eccentric,adjustably secured to the planetary frame, will be brought into positionto operate the movable arm 108 of a snapover switch assembly 110 whichincludes two contact means, said switching means remaining in thelast-operated position for control purposes. Upon an actuation of theswitch arm 108 by the adjustable stop 106, a circuit will be completedenergizing the operating solenoid 112, whose function it is to recockthe spring and simultaneously move the planetary gear assembly to theopposite limit of movement. This is accomplished through a linkagesystem best shown in Figure 2. It will be seen that the plate 60 of theplanetary assembly carries an elongated extension arm 114, which extendsoutwardly on the opposite side of the pivot and has pivotally connectedthereto a link 116. A lever 118 pivoted at 120 on the main frame of thetuner and adjacent its center has one end pivotally connected at 122 tothe link 116. The opposite end of the lever 118 is pivotally connecteddirectly to the solenoid armature 124. Thus when the spring has movedthe planetary assembly to its limit in one direction through the springpressure on the tang 104, the solenoid will, through the linkage justdescribed, rotate the planetary assembly in the opposite direction orclockwise, as viewed in either Figure 2 or Figure 5 to recock or chargethe spring. When the solenoid has moved the planetary assembly to theopposite extreme position, a second adjustabe stop 126 on the carriageis brought into contact with the actuating snapover arm 108 of the limitswitch and throws it to its opposite position, opening the solenoidcircuit to deenergize the same, and the mechanism will thus proceedthrough its next scanning cycle unless stopped by a signal.

Not only is it desirable to provide means for automatically scanning andindexing the tuning means, but it is also desired to simultaneouslyprovide manual driving means for the same tuning means. The manual drivein this instance consists of a manually adjustable knob 128 connectedthrough a flexible cable assembly 130 to a worm 132, supported forrotation on the frame. The worm is so located as to engage gear 42 andeither rotate the same or lock it against rotation.

The indexing of the mechanism when it is operated automatically fortuning purposes is accomplished through physical engagement between oneof the blades of the governor 58 and a pivoted arm 134- which is rigidlyconnected to and carried by the armature 136 of the control relay 138.It might be mentioned at this point that during tuning, relay 138 ismaintained energized as long as no signal appears in the receiver, butupon the appearance of such a signal this control relay is deenergized,permitting a small spring 140 to pull the armature away from the relayand cause the pivoted arm detent 134 to fall into engagement with theblades of the governor and stop the same. If the operator does notparticularly approve of the program being received by the stationindexed, he may move on to the next station merely by pushing inwardlyon the switch bar 142, movably mounted in a casing 144 in the front ofthe turner, said bar 142 being spring biased outwardly and its motionoperating a control switch 146 which again causes the energization ofrelay 138 to retract the detent from the governor and permit the driveto continue. Of course, when the automatic mechanism is not beingutilized and the receiver is being tuned manually, the detent remains inlocked position and the gear train stationary.

Specifically describing the operation of the driving mechanism duringthe two above identified types, either manual or automatic, let it firstbe assumed that it is desired to operate the mechanism automatically. Inthis case the worm 132 engaging the periphery of the gear 42 maintainsthe same locked-in position. The spring 102, however, tends to cause theplanetary carriage and assembly to move around its pivot, and as it doesso the rotation of gear 88, which walks around the periphery of the gear42 drives the large gear 72 mounted on the same shaft. Through itsengagement with gear 88 and other gearing previously described, thiscompletes the drive to the governor, which rotates at a desired speed.When the incoming signal causes the relay 138 to be deenergized, thedetent 134 drops into physical engagement with the first vane of thegovernor to arrive at that position and indexes the tuner. The circuitsfor indexing these signal seeking tuners do not form a part of thepresent application but are similar to those disclosed in copendingapplication Serial No. 106,223, entitled Signal Seeking Tuner, filedJuly 22, 1949, in the name of James H. Guyton, which issued September15, 1953, as Patent No. 2,652,486. It will be noted in this connectionthat the drive between gear 855 and gear 72, both mounted on shaft 68,is a frictional drive through friction disc 84 and dished wheel 74,ratchet wheel 82 and pawl 92 on gear 72. When the planetary assembly hasreached the limit of movement caused by the spring drive 102 and thesolenoid is energized for quick return, the pawl and ratchet connectionpermits such quick return in the opposite direction, the pawl 92 slidingover the teeth of the ratchet wheel 82 to its opposite extreme position.Thus we have a drive in one direction and a quick return in theopposite.

If it is desired to tune the set manually through rotation of thecontrol button 128, the detent 134 will remain in contact with the vanesof the governor, locking the main gear train against any rotation andwith it, of course, gear 38 and pinion 40. However, rotation of themanual button 128 will cause the Worm 132 to rotate, thus rotating theworm wheel 42. Gear 88 in mesh therewith will be turned, again drivinggear 72 through the friction connection above described, and gear 72,which is in mesh with gear 40 on shaft 36, and since that is lockedagainst rotation will tend to walk around the same. This will cause theplanetary assembly to move around the axis of shaft 36 and tune thereceiver. If the operator continues to rotate the knob 128 after themechanism has reached a limit of movement, then the friction drive 84-86will slip and prevent damage to the device.

Means are also provided by which the movement of the crossbar assemblywill actuate an indicating mechanism so that the operator will know inwhich part of the band the tuner is located. This indicating mechanismconsists of a dial 148 mounted in the front of the housing 144- belowthe switch 142 and calibrated with the identifying numerals for thespectrum covered. A movable needle 150 carried by the end of an arm 152moves behind the dial 148 and gives the desired indication. The arm 152has a pin 154 at its rearmost end, which is adapted to slide in a slot156 in a bracket 158 on the frame. This is to provide a pivotal supportand at the same time one capable of longitudinal movement, so that theneedle 150 may have relatively straight line motion behind the dialplate. A bellcrank 161i pivotally mounted on the frame through a shaft162 has one arm pivoted at 164 to the arm 152 at substantially midway ofits length. The opposite arm of bellcrank is connected through a link166 to an adjustable arm 168 on the crossbar assembly 10. The arm 163 ispivoted as at 170 to the crossbar assembly and may be adjusted aboutthis pivot through an adjusting screw 172 which is provided to cause theneedle 156 to be indexed properly. The shaft 162, upon which thebellcrank is pivoted and to which it is rigidly affixed, is springbiased in one direction through the use of an arm 174, likewise rigidlysecured to shaft 162 and rotatable with it, said arm 174 having a coilspring 176 connected thereto, the opposite end of which is secured tothe frame. Thus, as the crossbar assembly moves back and forth to tunethe receiver, it drives through a linkage and bellcrank the arm 152 togive an indication of the tuner position. Spring 176 acts in parallelwith power spring 102 and provides part of the power of driving thetuning member and gear train, plus biasing out backlash through themechanism from the pointer to the gear train. This biasing eifectprovides eccentric loading to the tuning carriage 10 and 18, forcingbearings 26 and 22 to ride rod 16 with side thrust, eliminating play atthese points.

On the left hand side of the front panel, as shown in Figure 1, a secondcontrol knob 178 is provided which controls the off-on and volumecontrol means 130. It will thus be evident that we have provided atuning mechanism for a radio receiver which can be operatedautomatically to scan a desired frequency spectrum and which is indexedby the appearance of an incoming signal, and that at any time or in anylocation of the tuning means, a manual drive is likewise provided fortuning the receiver manually.

We claim:

In means for tuning a radio receiver over a predetermined band having amovable tuning member mounted in a frame, indicating means mounted forscanning movement on the frame, permanently afiixed linkage meansinterconnecting the tuning means and the indicating means, screwthreaded adjustable abutment means on the movable tuning member engagingsaid linkage means to change the relative position of the tuning memberand indicating means to provide for properly setting the indicatingReferences Cited in the file of this patent means with respect to thetuning mernher by movement UNITED STATES PATENTS of the ad ustablemeans, and spring biasing means to urge a portion of the linkage meansagainst said abutment 2188136 Lmdsay Q 1940 means and to urge theindicator in one direction to elimi- 5 2190059 Edwards 1940 mate in thelinkage means Mahnken 2,499,573 Dunn Mar. 7, 1950 2,706,787 Sperber Apr.19, 1955

